Various embodiments of a laminated support mat are described herein. In particular, the embodiments described herein relate to an improved laminated support mat and a method of manufacturing such an improved laminated support mat.
The construction industry utilizes solid sawn wood and wood panel members in a variety of forms to aid in the erection of buildings, roads, and bridges. For example, temporary road panels and crane mats are often constructed using solid-sawn hardwood timbers or some species of softwoods. These panels are used to form a temporary lightweight roadway or foundation to facilitate vehicular and equipment travel as may be required in construction operations. Other industry users of such mats include users in the field of pipeline, utility, transportation, oil, and infrastructure.
As shown in FIG. 1, a conventional road panel, shown generally at 10, is formed by using a plurality of solid sawn timber elements 12. Typically, four pieces of solid sawn timber 12 are used, each having a cross-sectional dimension ranging from about 8 inches by 8 inches to about 12 inches by 12 inches, with a length of 16 feet. The four pieces of timber 12 are usually bolted together using bolts 14 to form the temporary road panel 10 having an assembled dimension of 4 feet by 1 foot by 16 feet. Several panels may be placed side by side over existing ground to form a temporary roadway or to support cranes on a construction site. Ground conditions under the panels vary greatly and may include, for example, sand, clay, wetlands, and possibly a considerable amount of water. Another conventional wood mat utilizes smaller dimensional lumber and utilizes nails, carriage bolts, or steel rods as a fastening system. All of these systems have mechanical fastening systems to transfer stresses between components. Additionally, U.S. Pat. No. 4,932,198 discloses a compound timber-metal stressed deck with metal plates inserted between the timbers.
The hardwood panels are typically discarded at the end of the construction project, or they may be re-used if they are in relatively good condition. The longevity of the panels may be as little as six months to one year, depending on the length of the construction project and the environmental conditions to which the panels are subjected. The wood panels are typically untreated with preservative chemicals because of environmental concerns. Hardwoods are typically used because of their superior wear resistance to heavy truck and other construction equipment traffic. In addition to road panels and crane mats, other applications for the hardwood panels include decks over steel girders for temporary bridges, and soldier piles.
Support mats are known to deflect or bend when a load is applied to an upper or load-bearing surface of the support mat. The vertical distance (perpendicular to the length of the wood members used in the support mat) that a support mat deflects will vary with the length of the support mat and the distribution of the load applied to the load-bearing surface of the support mat. A mat having a length of about 14 feet and a width of about 8 feet may, for example, deflect within the range of from about 2 inches to about 4 inches, although a mat may deflect less than 2 inches or more than 4 inches. Upon removal of the applied load, the support mat will return to a substantially planar shape.
Some support mats may be reinforced with steel or other metal beams. These steel beams are the same length as the mat and may be attached to the outboard edges of the support mat or at various intervals between the wood members that comprise the support mat. See for example support mats manufactured by Lister Industries Limited (http://www.listerindustries.com; accessed Aug. 23, 2012). The steel beams may provide additional strength to the support mat and reduce wear and tear on the wood members from handling, moving, etc. when the support mat is used in a field environment. Such a steel reinforced support mat will also deflect when a load is applied to an upper or load-bearing surface of the support mat. However, upon removal of the load, the steel reinforcement will not fully recover to its original shape and the support mat will experience a permanent deflection. Therefore, it would be desirable to provide an improved laminated support mat for supporting heavy equipment.